U.S. patent number 6,300,455 [Application Number 09/319,846] was granted by the patent office on 2001-10-09 for cross-linkable mixtures and method for producing same.
This patent grant is currently assigned to GE Bayer Silicones GmbH & Co. KG. Invention is credited to Emile Box, Rolf Haselhorst.
United States Patent |
6,300,455 |
Haselhorst , et al. |
October 9, 2001 |
**Please see images for:
( Certificate of Correction ) ** |
Cross-linkable mixtures and method for producing same
Abstract
Novel crosslinkable mixtures having improved room temperature
stability comprising platinum compounds or an elemental platinum,
and at least one sterically complicated substituted triaryl
phosphite.
Inventors: |
Haselhorst; Rolf (Leverkusen,
DE), Box; Emile (Dormagen, DE) |
Assignee: |
GE Bayer Silicones GmbH & Co.
KG (Erkrath, DE)
|
Family
ID: |
7816401 |
Appl.
No.: |
09/319,846 |
Filed: |
August 19, 1999 |
PCT
Filed: |
December 17, 1997 |
PCT No.: |
PCT/EP97/07084 |
371
Date: |
August 19, 1999 |
102(e)
Date: |
August 19, 1999 |
PCT
Pub. No.: |
WO98/29497 |
PCT
Pub. Date: |
July 09, 1998 |
Foreign Application Priority Data
|
|
|
|
|
Dec 30, 1996 [DE] |
|
|
196 54 690 |
|
Current U.S.
Class: |
528/31; 524/151;
524/862; 528/15; 524/710; 528/32 |
Current CPC
Class: |
C08K
5/526 (20130101); C08K 5/526 (20130101); C08L
83/04 (20130101) |
Current International
Class: |
C08K
5/00 (20060101); C08K 5/526 (20060101); C08G
077/08 () |
Field of
Search: |
;528/15,31,32
;524/862,710,151 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Moore; Margaret G.
Attorney, Agent or Firm: Norris McLaughlin & Marcus
Claims
What is claimed:
1. Crosslinkable mixture, storable in the presence of ambient air
and containing the following components:
a) at least one polysiloxane, which contains at least two
olefinically or acetylenically unsaturated multiple bonds,
b) at least one polyhydrogensiloxane, which contains at least two
hydrogen atoms bonded directly to the silicon atom,
c) at least one metal complex for catalyzing hydrosilyation,
d) at least one phosphorus compound of the general formula
P(OR).sub.3 where R=C.sub.9 C.sub.31 -alkylaryl, wherein R may have
different definitions within one molecule, and
e) optionally water, other further auxiliary substances or a
combination thereof.
2. Crosslinkable mixture according to claim 1, wherein component c)
is a Pt compound, a platinum complex or elemental platinum on a
support substance.
3. Crosslinkable mixture according to claim 1, wherein component c)
is a platinum/vinylsiloxane complex in which the siloxane contains
at least two olefinically unsaturated double bonds.
4. Crosslinkable mixture according to claim 1, wherein component d)
is a compound of the formula: ##STR2##
where
R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5 are each selected from
the group consisting of H, C.sub.n H.sub.2n+ where n=3-15, C.sub.a
H.sub.2a-1 where a=3-15, and C.sub.n F.sub.2n+1,
wherein
R.sup.1, R.sup.2, R.sup.3, R.sup.4 and R.sup.5 are identical or
different and not all of the radicals R.sup.1, R.sup.2, R.sup.3,
R.sup.4 and R.sup.5 represent H.
5. Crosslinkable mixture according to claim 4, wherein at least one
of R.sup.1, R.sup.2, R.sup.3, R.sup.4 and R.sup.5 is a tertiary
alkyl group.
6. Crosslinkable mixture according claim 1, further comprising an
organic solvent.
7. Crosslinkable mixture according to claim 1, wherein components
a) and b) are present in a ratio by weight such that the ratio
SiH:Si-vinyl is between 0.01 and 300, the concentration of
component c) is between 0.1 and 1000 ppm, the concentration of
component d) is 0.0001% to 5%, in each case with reference to the
total weight of the mixture.
8. Process for preparing the crosslinkable mixture of claim 1,
wherein components a) and d) are mixed, then component c) and
finally component b) are added.
Description
The present invention relates to crosslinkable mixtures and a
process for preparing them.
When using addition crosslinking silicone rubber systems, the
problem generally arises that the reactive mixture, once prepared,
has a finite rate of curing even at room temperature. This can be a
nuisance, in particular when the machines have to be shut down for
a relatively long time due to technical difficulties or for other
reasons. In this case, reactive silicone rubber mixtures left in
the machines crosslink even at room temperature which means that
very costly cleansing procedures have to be performed before the
process can be started up again.
For this reason, there has long been a market need for addition
crosslinking silicone rubber systems which ideally do not cure at
room temperature at all and have the highest possible rate of
reaction under the processing conditions.
In order to achieve this objective, so-called inhibitors are
normally added to the rubber systems. One group of inhibitors
comprises organophosphorus compounds. Thus, for example, in DE-A-3
635 236, the use of cyclometallised platinum phosphite complexes
for increasing the storage-stability at room temperature is
described. The catalyst inhibitor complexes mentioned there do
increase the pot life at room temperature, but they have the
disadvantage that they are complicated to prepare, which is
associated with additional production costs. EP-A-662 490 describes
general organophosphorus compounds as inhibitors in addition
crosslinking silicone systems. The aliphatic and aromatic
phosphines mentioned there, however, have the disadvantage that
they cause a clear reduction in the rate of reaction under the
processing conditions (T=120 to 170.degree. C.). DE-P 19532316.5
describes crosslinkable addition crosslinking mixtures which
contain, in addition to a hydrosilylation catalyst, an
organophosphorus compound and an inhibitor. The adjustment
described there, using a 2-component system, however, is
complicated. Mixtures which are fully inhibited at room temperature
and in which there is no effect on the rate of reaction under the
conditions of curing with an additive, have not hitherto been
disclosed.
There is therefore the object of providing suitable mixtures for
lowering the activity of the catalyst at room temperature, even in
rapid, addition crosslinking silicone systems, without extending
the curing times under the reaction conditions.
In addition, the mixture should be as simple as possible, i.e. it
should comprise the smallest possible number of components.
It has now been found, that the problems in addition crosslinking
polysiloxane mixtures can be solved if these contain Pt compounds
or elemental Pt or any other hydrosilylation catalysing substance
and at least one sterically complicated substituted triaryl
phosphite of the type described in more detail below. The mode of
action of the organophosphorus compound as inhibitor becomes closer
to that of an ideal inhibitor (switch function, threshold
characteristic) the more sterically complicated is the aromatic
group R.
The invention therefore provides crosslinkable mixtures containing
the following components
a) at least one polysiloxane, which contains at least two
olefinically or acetylenically unsaturated multiple bonds,
b) at least one polyhydrogensiloxane, which contains at least two
hydrogen atoms bonded directly to the silicon atom,
c) at least one substance for catalysing the hydrosilylation,
d) at least one phosphorus compound of the general formula (I):
P(OR).sub.3 where R=C.sub.7 -C.sub.31 -alkylaryl,
wherein R may have different definitions within one molecule,
and
e) optionally further auxiliary substances.
Component a) in the context of the invention is preferably a
cyclic, linear or branched polysiloxane which is built up from
units of the general formula (II)
Here, R.sup.3 represents a C.sub.2 -C.sub.8 -alkenyl radical, e.g.
vinyl, allyl, 1-butenyl, 1-hexenyl etc. The alkenyl radicals may be
bonded to silicon atoms within the chain or right at the end.
R.sup.4 is a monovalent, saturated hydrocarbon radical with up to
10 carbon atoms from the group of substituted and unsubstituted
alkyl, aryl, and arylalkyl radicals. Examples of these monovalent
radicals R.sup.4 are methyl, ethyl, propyl, isopropyl, butyl,
octyl, etc., cyclobutyl, cyclopentyl, cyclohexyl etc., phenyl,
tolyl xylyl naphthyl, etc., benzyl, phenylethyl, phenylpropyl. The
following conditions are placed on the integers a and
b:0.ltoreq.a.ltoreq.3 and 0.ltoreq.b.ltoreq.3 and
0.ltoreq.a+b.ltoreq.4. The number a is preferably 0 or 1. In the
radicals R.sup.4 in the present invention, some or all of the
hydrogen atoms may be substituted by fluorine and/or chlorine,
bromine, or iodine atoms or cyano groups. This means that R.sup.4
may also represent, for example, a chloromethyl, trifluoropropyl,
chlorophenyl, dibromophenyl, cyanoethyl, cyanopropyl or cyanopropyl
radical.
Using nomenclature which is familiar to a person skilled in the
art:
M:(CH.sub.3).sub.3 SiO.sub.1/2
D:(CH.sub.3).sub.2 SiO.sub.2/2
T:(CH.sub.3)SiO.sub.3/2
M.sup.Vi :(CH.sub.2.dbd.CH)(CH.sub.3).sub.2 SiO.sub.1/2
D.sup.Vi :(CH.sub.2.dbd.CH)(CH.sub.3)SiO.sub.2/2
the following may be cited as examples of component a):
M.sub.2 D.sub.100 D.sub.3 .sup.Vi
M.sub.2.sup.Vi D.sub.180
M.sup.Vi MD.sub.100 D.sub.3.sup.Vi
T.sub.5 D.sub.550 M.sub.7.sup.Vi
T.sub.3 D.sub.500 M.sub.2.sup.Vi M.sub.3
T.sub.6 D.sub.300 D.sup.Vi M.sub.4.sup.Vi M.sub.4
M.sub.2.sup.Vi D.sub.1500
M.sub.2.sup.Vi D.sub.4000 D.sub.50.sup.Vi and
M.sub.2 D.sub.2000 D.sub.5.sup.Vi
The molar proportion of unsaturated radicals of the type R.sup.3
may be chosen to have any value.
The molar proportion of unsaturated radicals of the type R.sup.3 in
component a) should preferably be between 10.sup.-3 and 10 mmol per
gram. The expression `between` always includes the particular
limiting values cited, both here and in the text which follows. The
viscosity of component a) is preferably between 10.sup.-3 and
1.000.000 Pa.s at 25.degree. C.
Component b) in the context of the present invention is a
polysiloxane which is built up from units of the general formula
(III)
wherein R.sup.4 is defined in the same way as above and R.sup.4 may
optionally also be defined in the same way as R.sup.3. The
stoichiometric indices c and d are integers where
0.ltoreq.d.ltoreq.3 and 0.ltoreq.c.ltoreq.2 and
0.ltoreq.c+d.ltoreq.4. Preferably, 0.ltoreq.c.ltoreq.1.
Using nomenclature which is familiar to a person skilled in the
art
Q:SiO.sub.4/2
M.sup.H :H(CH.sub.3).sub.2 SiO.sub.1/2
D.sup.H :H(CH.sub.3)SiO.sub.2/2
the following may be cited as examples of component b):
M.sub.2.sup.H D.sub.10,
M.sub.2 D.sub.10 D.sub.10.sup.H,
M.sub.2.sup.H D.sub.20 D.sub.10.sup.H,
M.sub.2.sup.Vi D.sub.11.sup.H,
M.sub.2 D.sub.3.sup.Vi D.sub.8.sup.H, and
QM.sub.1,3-1,8.sup.H D.sub.0,1,
(M, D, M.sup.Vi and D.sup.Vi are defined in the same way as for
component a)).
The molar proportion of hydrogen atoms directly bonded to a silicon
atom in component b) may be chosen to have any value at all.
In component b), the molar proportion of hydrogen atoms directly
bonded to a silicon atom is preferably between 0.01 and 17 mmol,
more preferably between 0.1 and 17 mmol and in particular is
between 1 and 17 mmol per gram of component b).
In the overall mixture described, components a) and b) are
preferably present in a ratio by amounts such that the molar ratio
of hydrogen atoms directly bonded to a silicon atom (SiH) in
component b) to unsaturated radicals (Si-vinyl) in component a) is
preferably between 0.05 and 20, more preferably between 0.5 and 10
and in particular between 1 and 5.
Component c) in the context of the invention preferably includes
the elements platinum, rhodium, iridium, nickel ruthenium and/or
palladium, as the element on a support substance or in the form of
their compounds. Platinum compounds or platinum complexes such as,
for example, H.sub.2 PtCl.sub.6, platinum/olefin complexes,
platinum/alcoholate complexes, platinum/vinylsiloxane complexes or
also elemental platinum on a support substance such as e.g.
activated carbon, Al.sub.2 O.sub.3 or SiO.sub.2 are preferred.
Component c) is, in particular, a platinum/vinylsiloxane complex.
Platinum/vinylsiloxane complexes preferably contain at least 2
olefinically unsaturated double bonds in the siloxane, see e.g.
U.S. Pat. No. 3 715 334.
The expression siloxane also includes polysiloxanes, i.e. for
example also vinylpoly-siloxanes. The proportion of component c) in
the overall mixture is preferably between 1 and 1000 ppm, more
preferably between 1 and 500 ppm and in particular between 1 and
100 ppm.
Component d) in the context of the invention is an organophosphorus
compound of the type P(OR).sub.3. R may represent different
entities within one molecule.
A compound of the following formula is preferred: ##STR1##
where
R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5 =H, C.sub.n H.sub.2n+1
and n=1-15, C.sub.a H.sub.2a-1 and a=3-15 and/or--C.sub.n
F.sub.2n+1,
wherein
R.sup.1, R.sup.2, R.sup.3, R.sup.4 and R.sup.5 may be identical or
different and not all of the radicals R.sup.1, R.sup.2, R.sup.3,
R.sup.4 and R.sup.5 represent H.
The aliphatic radicals mentioned may be linear or branched, the H
atoms contained therein may optionally be substituted by groups
such as --NH.sub.2, --COOH, --F, --Br, --Cl, --CN, --C.sub.6
H.sub.5, --C.sub.6 H.sub.4 (CH.sub.3).
Sterically complicated radicals in the context of the invention are
also substituted or unsubstituted heteroaromatic compounds as well
as substituted or unsubstituted polyaromatic compounds as well as
polyaromatic compounds containing heteroatoms.
Component d) in the present invention is preferably added in an
amount by weight of 1 ppm to 50 000 ppm, with reference to the
total weight of mixture, more preferably 10 ppm to 10 000 ppm and
in particular between 20 ppm and 2000 ppm.
Components d) can be prepared, for example, by the processes
described in Methoden der organ. Chemie, Houben-Weil, vol. XII/2,
1964, 4th ed. p. 59-61.
Auxiliary substances (component e) in the context of the invention
are, for example, polysiloxane resins which are built up from
fundamental units of the general formula (II) and (III), fillers
which have a positive effect on the mechanical and electrical
properties of the cured mixture in accordance with the invention
such as, for example, pyrogenic and precipitated silicas with a BET
surface area of 50 to 500 m.sup.2 g. These types of fillers may be
surface-modified, for example with organosilicon compounds.
Modification may also be achieved during incorporation into the
polymer by adding, for example, .alpha., .omega.-OH terminally
stopped oligosiloxanes or polysiloxanes or hexa-methyldisilazane or
1,3-divinyl-1,1,3,3-tetramethyldisilazane while adding water.
Furthermore, substances such as, for example, diatomaceous earths,
finely divided quartz powder, amorphous silica or carbon black, as
well as Al(OH).sub.3 or oxides which can be ceramicised, etc., may
be used as fillers.
In another embodiment, mixtures according to the invention also
contain water or an organic solvent.
In a preferred embodiment of the invention, components a) and b)
are preferably present in a ratio by weight such that:
the ratio SiH:Si-vinyl is between 0.1 and 10,
the concentration of component c) is between 1 and 1000 ppm,
the concentration of component d) is between 0.0001 and 5%,
wherein data referring to amounts are each with reference to the
total weight of the mixture.
This invention also provides a process for preparing crosslinkable
mixtures according to the invention. In this, components a) and d)
are preferably mixed and then component c) and finally component b)
are added. It is also possible to mix components a) and d) and add
component b) and lateron component c). The addition of component c)
ensures (apart from the composition) that the rate of reaction is
reduced.
The invention also provides use of phosphorus compounds of the
formula I as an inhibitor and the use of a mixture of at least one
phosphorus compound of the formula I and a Pt compound or elemental
Pt to control the rate of crosslinking in addition crosslinking
silicone systems.
The following examples are used to explain the invention. The
invention is not, however, restricted to the examples.
WORKING EXAMPLE
In the following examples, all data relating to weight and
percentages, unless stated otherwise, are with reference to the
weight of the entire mixture.
The compounds used can be defined as follows:
Chemical Si-Vi Si-H con- Name composition Viscosity concentration
centration Poly- M.sup.V1.sub.2 D.sub.n 1000 Pa s 0.005 mmol
g.sup.-1 -- siloxane A Poly- M.sub.2 D.sub.n D.sup.V1.sub.m 1150 Pa
s 0.024 mmol g.sup.-1 -- siloxane B Poly- M.sub.2 D.sub.n
D.sup.H.sub.m 35 mPa s -- 4.3 mmol siloxane C g.sup.-1 Poly-
M.sup.V1.sub.2 D.sub.n 10 Pa s 0.05 mmol g.sup.-1 -- siloxane D
The basic mixture used consists of:
55 wt. % of polysiloxane A,
19 wt. % of polysiloxane B and
26 wt.% of surface-modified pyrogenic silica.
The inhibitor mix used is composed as follows:
99.915 wt. % of basic mixture and
0.085 wt. % of an organophosphorus compound of the type P(OR).sub.3
and
the catalyst mix used consists of:
99.88 wt.% of polysiloxane D and 0.22 wt. % of Pt (in the form of a
vinylsiloxane complex)
EXAMPLE 1
The amounts of inhibitor mix and catalyst mix specified below were
added to the parts of basic mixture given in Table 1. The amount of
catalyst mix was selected so that the concentration of metallic Pt
in all the mixtures was 10 ppm, with reference to the weight of the
entire mixture. The amount of inhibitor mix was selected so that
the molar ratio of organophosphorus compound to Pt complex was 2:1
in all the mixtures.
Finally, 1.3 g of polysiloxane C were added. The molar ratio of
vinyl groups directly bonded to Si atoms to H atoms directly bonded
to Si atoms was 1:2.5 in all the mixtures.
TABLE 1 Amounts used, given as parts by wt. Initial amount R =
4-tert.-butyl- R = 2,4-ditert.- weighed out R = phenyl phenyl
butylphenyl Basic mixture 95.6 93.5 9.2 Inhibitor mix 4.2 6.5 8.8
Catalyst mix 0.5 0.5 0.5
All the mixtures had a pot life of more than four weeks at room
temperature.
Cure-meter curves were plotted for each of these mixtures at
temperature T=140 .degree.C. and the t.sub.60 -times were
determined.
Table 2 gives the chemical structure of R in the organophosphorus
compound of the type P(OR).sub.3 and also gives the t.sub.60 -time
at T =140 .degree.C.
TABLE 2 R = t.sub.60 -time at T = 140.degree. C. phenyl 19.73
4-tert.-butylphenyl 9.69 2,4-di-tert.-butylphenyl 1.22
The systems are faster the more sterically complicated is the
radical R in the organophosphorus compound of the type
P(OR).sub.3.
* * * * *